1. Field of the Invention
This invention pertains to tub grinders for grinding waste material. More particularly, this invention pertains to a cover and other elements for reducing debris ejection out of the tub grinder during operation.
2. Description of the Prior Art
Tub grinders for grinding organic waste material (such as trees, brush and the like) are well known. An example of such is shown in commonly assigned U.S. Pat. No. 5,507,441 dated Apr. 16, 1996. Another example is shown in U.S. Pat. No. 5,419,502 dated May 30, 1995.
Tub grinders include a rotary grinding member which is mounted on a frame for rotation about a horizontal axis. A rotating tub surrounds the grinding member. The tub rotates about a general vertical axis. Debris is deposited in the rotating tub and the rotary grinding member grinds the debris.
Tub grinders are powerful machines. Commonly, a tub grinder may be powered by a 400 horsepower motor with the grinder rotating at about 2100 rpm.
Tub grinders are intended for use in grinding organic waste material (e.g., brush, wood, grass, leaves, paper, etc.). Occasionally, through misuse of the tub grinder or the like, metal or other undesired material may be admitted to the tub grinder. The rotary tub grinder may eject material from the tub resulting in projectiles being thrown from the tub during its use.
U.S. Pat. No. 4,585,180 shows a hood (item 34 in FIG. 4 of the ""180 patent) which serves to deflect material downwardly. Such hoods are positioned directly above the grinding member and have been used to limit the amount of material which may be deflected by the grinding member. However, even with such hoods, material may still be deflected out of the tub.
Other designs for reducing the amount of debris projection have included a deflection plate mounted on an interior wall of the tub where the deflection plate was angled both radially inwardly and downwardly toward the central axis of the rotating tub.
Notwithstanding the prior techniques for reducing deflection of material from a tub, there is an increased need for providing novel means for reducing the amount of debris material being deflected for a tub grinder. It is an object of the present invention to provide such an apparatus.
According to a preferred embodiment of the present invention, a tub grinder is provided which includes a frame having a generally horizontal floor. A tub is mounted on the frame with the wall of the tub surrounding a floor opening and with the tub having a lower end in close proximity to the floor. An upper end of the tub is open to define a tub opening. The tub is rotated about a generally vertical axis. A grinding member is mounted on the frame for a rotation about a generally horizontal axis. A portion of a circumferential area of the grinding member is exposed through the floor opening. A deflection plate is secured to the floor and extends partially over a first side of the floor opening to partially cover the grinding member. A deflection cover is secured to the frame and positioned above the tub opening covering only a portion of the tub opening.